Dobby mechanism



United States Patent 7 Appl. No.

Thomas llindle;

Vincent Plnder Banks, Blackburn, England 765,586

Oct. 7, 1968 Nov. 24, 1970 llindle, Son & Company Limited Blackburn,England Oct. 7, 1967 Great Britain Inventors Filed Patented AssigneePriority DOBBY MECHANISM 11 Claims, 6 Drawing Figs.

US. CL...

[56] References Cited UNITED STATES PATENTS 2,425,676 8/1947 Hindle139/55 3,115,899 12/1963 Hindle.. 139/76 3,144,883 8/1964 Short 139/55FOREIGN PATENTS 1,069,915 5/1967 Great Britain 139/66 518,109 3/1955ltaly 139/55 Primary Examiner-James Kee Chi Attorney- Roberts, Cushman &Grover ABSTRACT: A dobby mechanism comprising a double-acting slavecylinder coupled to each cam lever to effect the lifting and lowering ofthe cam lever in accordance to the shedding requirements or pattern.

Patented Nov. 24, 1970 Sheet Pqtnted' Nov. 24, 1970 3,542,082

Sheet 2 014 I Patented Nov. 24, 1970 I 3,542,082

Sheet 3 of 4 Patented" Nov. 24,1970

Sheet specification No. 904,322 describes an improved arrangement ofLeeming-type dobby which is capable of reliable operation in connectionwith wide and heavy looms such as are required for weaving paper-machinefelts, wherein much greater loads and forces are involved than in anordinaryloom, and which is responsive to a pattern record set for risersand falle rs, in place of the pattern record set for changes as is usualwith the ordinary [seeming-type dobby. Both purely mechanical andelectromechanical converter mechanismsQwhich enable the pattern recordto be set for risers and fallers instead of for changes, are describedin the patent specification aforesaid.

According to the aforesaid U.S,. patent, the camlevers are lifted by amechanicalrelay andlowered by gravity but under the control of therelay,'which relay is actuated by a rotary cam. By their verticalmovement, either up or down, the camlevers slide their respectivesegment-gears along the splined driving shaft, either into or out of thefixed planes of their as-' sociated crank-gears. During each revolutionof the loom crankshaft, the said mechanical relay first lowers all thepreviously lifted cam-levers (thereby shifting the associatedsegment-gears out of the planes of their mating crank-gears), thenpauses for a new selection to be made,'afte'r which the relay lifts thenewly selected cam-levers.(thereby shifting the segment gears into theplanes of their mating crankgears) and then retains them in thatposition while the gears turn in mesh, and change the positions of theheald shafts concerned. The necessity to lower all the previously liftedcam-levers prior to the new selection, even though some'of them may berequired to be lifted again for the next sequence, seriously restrictsthe crankshaft angles available. forthe up and down movements of I v toproduce the open-shedding sequence exactly as'indicated by the patternchain, or other form of record, set for risers and fallers. I

According to a further feature of the invention, a timing switchactuated bytheloom crankshaft, or equivalent shaft, controls the currentsupply to the whole of the paralleled electric control circuits, beingarranged to complete the said circuits so as to render them operativefor somewhat less than the angle of heald shaft dwell, and to interruptthe said circuits throughout rather more than the angle of change,during which latter angle the gears are actually turning in mesh. Thehand-operatedleveling lever, which lifts all thepattern-switchsensing'levers not already raised by the patternchain, may therefore beoperatedat any time in the crankshaft revolution without danger ofdamage 'or derangement, because any such operation of the leveling leverbecomes effective only as and when the timing switch closes, by whichtime the gears have the position switch are each provided withsingle-pole changeover contacts (or the equivalent) which serve toenergize an electric relay also provided with single-pole changeovercontacts, (or the equivalent) the two switches, the timing switch,

the relay and the said valve solenoids being interconnected to producethe desired open shedding sequence indicated by the the cam-levers,whichoperations,'including the intervening pause for the new selection,mustbe completedwithin the angle during whic'hfthe heald shafts. dwellintheiropemsh'ed positions. I I I I The object of the. present inventionisto provide improved means for actuating thesaid carn-lever's,wherebytheir actual movement, either up or down (as the case maybe) mayoccupynearly the entire angle of dwell of the heald shafts, and,furthermore, whereby the cam-levers make no down movements other thanthose essential for the effective operation of i supported in. the dobbyframes, while theprotruding end of the piston rod is hinged to thecam-lever, at a suitable distance from its fulcrum. The said cylinder ispreferably provided with cushioning means at both endsof the pistonsstroke, with internal stops against whichthe piston is retained by fluidpressure in either its extreme up or down position, until required tomake a further strokeinthe opposite direction.

According to another feature of theinvention, the flow of pressure fluidto and from the. said double-acting slave cylinder is controlled by atwo-position valve provided with two solenoids. This valve is adaptedtobe shot over in one direction or the other when one solenoid, or. theother, is mo mentarily energized, and after having been so shot over inpattern chain set for risers and fallers.

The invention will be described further, by way of example only, withreference to the accompanying drawings illustrating three embodimentthereof and in which:

F16 1 is a diagrammatic elevation of the mechanism for controlling thepositionof the cam lever of a dobby of the Leeming type; I

FIGS. 1a and are front elevations of cam formations provided in opposeddisposition in the cam lever;

FIG. is a schematic representation of one form of relay and theoperation thereof in positionally controlling the cam lever; I v

FIG, 3 is a view corresponding to that of F IG, 2 and shows analternative forniofrjelaymnd FICA is a viewaain corresponding to I l lG.2 and. showing a still further form of. relay.

axially on a splined shaft '13 in conventional manner via a shifter 14intoor out of mesh with a crank gear 15 according to a pattern sequenceis positionally controlled by a doubleacting slave cylinder l6mounted ona bar 17 secured in position on the loom framework (not shown).

I The segment gear 12, and its constructional and operational Irelationship with the various parts of the dobby mechanism in lifting orlowering the heald frames is well known in the art,

andis described in great detail in the-above -mentioned US.

of the cam surfaces 18'on the'lever 11 andthe cooperating cam followers19 on the shifter 14-, such means comprising the double-acting slavecylinder 16 and the control arrangements either direction remain in thatposition indefinitely until the I other solenoid is next momentarilyenergized, and so on.

According to another feature of the invention,the two soleno'id' coilsof each valve are controlled by an electric patternswitch responsive tothe weaving patternrecord in combination with an electricposition-switch responsive to the position,

either up or down, of the associated heald shaft, or equivalent thereof.

As illustrated the said slave cylinder is pivotally connected at one endto the through bar 17 by a pin 16a and has projecting from its oppositeend a piston rod 16b the inner end of which is fixed to a piston and theouter end of which is pivotally connected tothe cam lever 11 by a pinlla. The 70 cylinder 16 contains cushioning means at both ends and stops16d against which the piston is held by the fluid pressure at eitherextreme position, the cushioning means and stop means indicated at 16cand 1611 in FIG. 2.

One control arrangement is'shown in FIG. 2 and will be seen to comprisea two position valve 20 provided with two solenoids2l, 22, the solenoids21,22 being adapted, upon momentary energization, to set the valve inone or other of two positions, such valve feeding pressure fluid to oneside or other of the piston of the slave cylinder 16 according to itsposition.

The electrical circuit for the two solenoids includes an electricpattern switch- PA responsive to the weaving pattern record, incombination with an electric position switch PO responsive to theposition of the associated heald shafts as indicated by the jack levers,the said switches PA, PO each being provided with double-pole changeovercontacts as indicated. A timing switch T is provided within theelectrical circuit of the control arrangement whereby the changein valvesetting is arranged to occur only at a predetermined time in the loomcycle.

It will be apparent from the control arrangement shown in FIG. 2 thateither thechange solenoid 21 or the no-change solenoid 22 will beenergized according to the relationship between the requirement of thepattern switch PA and the setting of the position switch PO, and theslave cylinder I6 will be actuated or not, as appropriate, to change theposition of the cam lever 11 to raise or lower the related jack lever23, and thus the position ofthe related heald frame.

An alternative control arrangement is shown in FIG. 3 and again includesa two position valve 20' having two solenoids 21', 22', associatedtherewith, the said valve-feeding pressure fluid to the slave cylinder16 as before. The electrical circuit for the solenoid differs from thatas shown in FIG. 2 in that instead of the pattern switch and positionswitch PA and PO respectively having double-pole changeover contacts,singlepole changeover contacts are provided and a solenoid 24 sensitiveto the relative positions of the pattern and position switches isincluded, which solenoid, according to its position, energizes thechange or no change solenoids 21', 22' at each loom cycle. In the caseof the .control arrangement of FIG. 3

the timing switch T has two contacts A and B, contact A closing shortlybefore contact B thus to ensure that the solenoid 24 is operated inadvance of the change or no-change solenoid as appropriate.

A still further alternative control arrangement is shown in FIG. 4, theelectrical circuit differing from that of FIG. 2 in that the patternswitch PA has single-pole changeover contacts, whilst the positionswitch PO has double-pole changeover contacts but with such contactsinterconnected in the manner illustrated..As with the arrangement ofFIG.'2 so the arrangement shown in FIG. 4 has a single timing switch T,and the functioning of the arrangement is similar.

It is an important advantage ofthis invention that the timing diagram ofthe dobby events may be arranged so as to be substantially symmetrical,thereby enabling the dobby to function correctly while the loomcrank-shaft and the dobby driven therefrom are temporarily reversed. a r

While the improved mechanism is suitablefor actuating vertical jacklevers in the general manner described in U.S. Pat. No.. 3,1 15,899, itis also particularly adapted for actuating horizontal jack levers, inwhich case it is preferred to construct the dobby in two parts, one ofwhich is disposed at each end of the loom structure. The electriccontrol enables the entire pattern chain and its driving arrangements tobe located at one'end of the loom from which electric signals areconveyed by simple circuitry to both parts of the mechanism.

As already mentioned, the dobby mechanism herein described is alsouseful for any other purpose where a member requires to be moved on atimed sequence between two limiting positions, with the advantage ofremote control when necessary.

We claim:

1. In a Leeming-type dobby mechanism embodying pairs of segment andcrank gears s'upportedon spaced parallel shafts, said segment gearsbeing movable laterally on their shafts into and out of engagement withtheir associated crank gears in accordance with the dictates of-apattern, and operable while in engagementwith the crank gears to imparta half revolution at a time thereto, a cam lever astrlde each segmentgear, said earn lever embodying cams operable by movement of the camlever towards the crank gear to shift the segment gear laterally out ofengagement with the crank gear and by movement away from the crank gearto shift the segment gear laterally into engagement with the crank gear;means supporting the cam lever for movement toward and from the crankgear comprising a fixed pivotat one end of the lever on which the leveris pivotally mounted, a reciprocal part at the other end of the lever towhich the other end is pivotally connected and a motor operable toeffect reciprocation of the reciprocal part in response to the dictatesof the pattern.

2. Apparatus according to claim I, wherein said motor comprises apivotally supported cylinder and piston assembly, and said reciprocalpart is rigidly connected at one end to the piston and pivotallyconnected at the other end to the lever.

. 3, Apparatus according to claim 2, comprising a two-piston valveoperable in one position to supply pressure'fluid to one end of thecylinder and in the other position to supply fluid pressure to the otherend of the cylinder, said valve in each of its positions being held inthat position by the pressure fluid supplied thereto to effect suchmovement.

4. Apparatus according -to claim 3, comprising two solenoids operable toeffect movement of the two-position valve to effect movement of thevalve from one end to the other and from the other end to the one, saidvalve being adapted to remain in its end position when shifted theretoby one solenoid until actuated by the other solenoid.

5. Apparatus according to claim 4, wherein the solenoids are operated bythe pattern comprising a position switch operable in series with thepattern switch to effect energization of the solenoids, said positionswitch being rendered operative only if the last position of the camlever associated therewith is such that the pattern dictates a changetherefore.

6. Apparatus according to claim 4, comprising a two-position solenoidoperable switch for effecting operation of said valve and a positionswitch associated with each jack lever operable in serial with thepattern switch to energize the solenoid switch only if the last positionof the cam lever associated therewith is such that the pattern dictatesa change therefore.

7. Apparatus according to claim 5, wherein the segment gear isconstantly rotated and the crank is intermittently rotated through apredetermined angle of rotation of the segment gear and is idle for apredetermined angular rotation of the segment gear, a timing switchoperable in series with the positioning and pattern switches through aperiod of somewhat greater duration than the period of rotation of thecrank gear to disable the positioning and pattern switches and operableduring a period of somewhat lesser duration than the period of dwell ofthe crank gear to actuate said switches.

8. Apparatus according to claim 5, wherein the pattern switch, positionswitch and solenoids are interconnected so that when the pattern switchand position switch are positioned for effecting lateral movement of thesegment gear a circuit will be completed to one of the solenoidsoperable to shift the two position valve to a position to supplypressure fluid to the lower end ofthe cylinder but if the positionswitch is not so positioned it will fail to complete the circuit to saidsolenoid.

9. Apparatus according to claim 8, wherein the position switches andpattern switches are each double-acting switches.

10. Apparatus according to claim 8, wherein the pattern switch is asingle-pole single-acting switch and the position switch is adouble-pole double-acting switch.

11. Apparatus according to claim 9, wherein the pattern switch andposition switch are single-pole single-acting switches and are operablyconnected by a solenoid operable double-pole double-acting switch in thesolenoid circuit.

